dcfldd
Enhanced version of dd for forensics and security.
TLDR
Copy a disk to a raw image file and hash the image using SHA256
$ dcfldd if=/dev/[disk_device] of=[file.img] hash=sha256 hashlog=[file.hash]
Copy a disk to a raw image file, hashing each 1 GB chunk
$ dcfldd if=/dev/[disk_device] of=[file.img] hash=[sha512|sha384|sha256|sha1|md5] hashlog=[file.hash] hashwindow=[1G]
